Method for lining boreholes for deep bores and device for carrying out said method

ABSTRACT

The invention relates to a method for lining boreholes for deep bores. A lining method, which makes a rapid process sequence possible with a substantially uniform borehole diameter, is characterized, according to the invention, in that the borehole is lined directly after boring with a hybrid material consisting of a fibrous material and a hardenable medium. The invention also relates to a device for carrying out the method.

The invention relates to a method for lining boreholes for deep bores.Furthermore, the invention relates to an apparatus for carrying out saidmethod.

Boreholes for vertical deep bores, that is to say bores which are driveninto the ground to a depth of more than 500 m, are formed in practice bythe “rotary method”, in which the rock to be penetrated is comminutedwith a scraping action by means of a rotating chisel and is continuouslyremoved by a flushing fluid which is pumped downward through the drillrod.

In the case of very deep bores, use is generally made of a drillingturbine which is arranged directly above the drill bit. In this method,the drill rod adjoining the drill bit counter to the drilling directiondoes not rotate with the drill bit but rather serves only for advancingthe bit and for supplying the flushing fluid.

Drill bits with diamond or sintered carbide edging have a durability of70 to 100 hours in customary ground conditions. In order to exchange andrefurbish the drill bit, the entire drill string then has to be pulledout of the borehole and dismantled in order subsequently to be loweredagain into the borehole with the new drill bit. In the conventional deepdrilling method, the drilling operation therefore proceedsdiscontinuously.

In order to prevent the borehole from caving in, the borehole has to besupported, which is carried out in the case of the conventional deepbores by casing. This is carried out in stages with a decreasing pipediameter in such a manner that, for example, in the case of an oil wellat a depth of 3000 m, first of all a pipe reaching to a depth of 5 m andhaving an outside diameter of 473 mm is introduced. After a drillingdepth of 150 m, a pipe known as a casing with an outside diameter of 340mm is pushed as far as the bottom of the bore and the intermediate spacebetween borehole wall and casing is filled with a cement slurry. At adrilling depth of 1500 m and at the final depth of 3000 m, furthercasing is carried out with casings which each have a smaller outsidediameter than the previous casing, and therefore the outside diameter ofthe final casing after the end depth is reached is only 140 mm.

Although this known deep drilling method has proven successful inpractice, the discontinuous lining or casing of the borehole wall isvery time-consuming. Furthermore, the borehole inside diameter whichdecreases in stages is not advantageous for all applications either.

Taking this as the starting point, the invention is based on the objectof providing a method for lining boreholes for deep bores, which makespossible a rapid working sequence with a borehole diameter remainingsubstantially constant.

According to the invention, the achievement of this objective ischaracterized in that the borehole is lined directly after the drillingwith a hybrid material consisting of a fiber material and a curablemedium.

By means of the direct lining according to the invention of the boreholeafter drilling, with a fiber-reinforced hybrid material, it is possiblefor the first time to provide a lining method which is continuous—ifpermitted by the drilling operation—and which furthermore permits liningof the borehole having a substantially constant borehole diameter.

According to a practical embodiment of the invention, it is proposedthat the curable medium is sprayed onto the fiber material. The sprayingmethod ensures that the fiber material is uniformly and rapidly wettedwith the curable medium.

In order to form said hybrid material which serves to line the boreholewall and consists of a reinforcing fiber and a curing medium, use ispreferably made of carbon fibers and concrete. Depending onrequirements, the borehole can be lined with one layer or with multiplelayers.

As an alternative to the mentioned carbon fibers and the concrete ascuring medium, it is also possible, of course, to use other fibermaterials and other curing media, such as, for example, plastics, forlining the borehole.

An apparatus according to the invention for carrying out the liningmethod according to the invention is characterized by a borehole liningmodule which has spraynozzles for applying a curing medium, and areinforcing fabric laying apparatus.

In order to secure the borehole and also in order to shield the boreholefrom groundwater-conducting layers, the borehole is continuously lineddirectly after the drilling. For this purpose, the borehole liningmodule has spray nozzles for applying a curing medium, such as, forexample, concrete, and a reinforcing fabric laying apparatus. In orderto form said hybrid material serving for lining the borehole wall andconsisting of a reinforcing fiber and a curing medium, use is preferablymade of carbon fibers and concrete. The fiber structure can bedischarged via a cone, via which the reinforcing fibers can be applieddirectly onto the borehole wall in order subsequently to be able to bewetted with the curing medium. Depending on requirements, the boreholecan be lined with a single layer or with multiple layers.

Of course, as an alternative to the carbon fibers mentioned and theconcrete as curing medium, use may also be made of other fiber materialsand other curing media, such as, for example, plastics, for lining theborehole.

The borehole lining module according to the invention is advantageouslysupplied via flexible pipe and/or hose lines, via which the module isconnected to supply devices outside the borehole, wherein the pipeand/or hose lines serve for the supply and removal of the materialsrelevant at least to the borehole lining module and for the feeding inof the electric supply lines. Each individual line of said flexible pipeand/or hose lines is preferably designed here as an endless line whichcan be kept ready on drums.

In addition to the electric supply lines, the flexible pipe and/or hoselines, via which the borehole lining module is connected to supplydevices outside the borehole, also contain data lines, for example a bussystem, via which at least the borehole lining module is connected to aworkplace outside the borehole.

According to the invention, via the data lines, in addition to thesystem parameters, such as, for example, feed speed and pumpingpressure, all of the ambient parameters in the borehole, such as, forexample, temperature, pressure, rock density and the like, can bedetermined via sensors coupled to the data lines and can be transmittedto the workplace in order to control at least the borehole liningmodule.

Further features and advantages of the invention emerge with referenceto the associated drawings in which an exemplary embodiment of a liningapparatus according to the invention is illustrated merely by way ofexample without restricting the invention to said exemplary embodiment.In the drawings:

FIG. 1 shows a schematic side view of a drilling system according to theinvention;

FIG. 2 shows a front view of the drill head according to FIG. 1, and

FIG. 3 shows a view according to FIG. 1, but showing the drilling systemin a borehole.

FIG. 1 shows a drilling system 1 for vertical deep bores, which drillingsystem essentially consists of a drill head 2, a safety module 3 and aborehole lining module 4, wherein the individual assemblies 2, 3 and 4are arranged one behind another rigidly or so as to be movable relativeto one another, depending on the application.

Although vertical deep bores are mentioned, it is possible, with themethod described below and the drilling system 1, also to direct thedrilling course from the vertical into a horizontal course if this isrequired. However, the main drilling direction is the deep verticalbore.

As is apparent from the arrangement, illustrated in FIG. 3, of thedrilling system 1 arranged in a borehole 5, the drilling system 1consisting of the drill head 2, the safety module 3 and the boreholelining module 4 is supplied via flexible pipe and/or hose lines 6, viawhich the drilling system 1 is connected to supply devices 7 outside theborehole 5. The pipe and/or hose lines 6 which serve for the supply andremoval of the materials relevant to the drilling system 1 and for thefeeding in of the electric supply lines, the individual pipe and/or hoselines 6 are designed as an endless line which can be kept ready ondrums.

The individual pipe and/or hose lines 6 are connected at certaindistances to spacers and thus form a feed-in package which is guidedinto the borehole 5. In order to be able to absorb the tensile forceswhich occur because of the dead weight of the pipe and/or hose lines 6and the weight of the drilling system 1, steel cables which areappropriately mounted outside the borehole 5 are preferably entrained.Furthermore, there is the possibility of securing floats to the pipeand/or hose lines 6, said floats absorbing the tensile loading since theborehole 5 is underwater during the drilling operation.

The drilling method and the borehole lining method are described belowwith reference to a chisel-less drilling method, in which the drill head2 is configured in such a manner that both high pressure water jetcutting and high frequency rock fragmentation can be carried outtherewith.

However, the borehole lining method described is independent of themanner of operation of the drill head 2. It is crucial for the liningmethod to be able to be active directly after the drilling.

As is apparent from FIG. 2, water outlet nozzles 8 for the high pressurewater jet cutting and sonotrodes 9 for transmitting high frequencyvibrations for the high frequency rock fragmentation are arranged on thefront end side of the drill head 2.

In order to ensure uniform and substantially extensive processing overthe entire borehole diameter of the rock to be penetrated, the entiredrill head 2, but at least an end plate 10 of the drill head 2, whichend plate is provided with the water outlet nozzles 8 and the sonotrodes9, is designed so as to be rotatable about the center axis.

For the sucking up of the drilling mud arising during the drillingoperation, the end plate 10 is provided with suction openings 17, viawhich the drilling mud can be sucked off and pumped out of the borehole5 by the pipe and/or hose lines 6.

In order to generate the high frequency pulses for the high frequencyrock fragmentation, piezo elements which are each coupled to anamplifying unit consisting of a sonotrode 9 and an amplitude transformerare arranged in the drill head 2. In order to protect the sonotrode 9from wear, said sonotrodes are advantageously coated, for example withpolycrystalline diamond.

The pumps for the high pressure water jet cutting and for sucking offthe flushing medium are arranged on the drill head 2 and/or on thesafety module 3. In order to increase the cutting action of the highpressure water jet, an abrasive agent, such as, for example, quartzsand, can be added to the water jet, the abrasive agent being suppliedto the drill head 2 via the flexible pipe and/or hose lines 6 and beingmixed with the water jet only in the water outlet nozzle 8 in order tokeep the wear on the lines as low as possible. The abrasive agent can beadded here continuously or else only from time to time.

By means of the combination of the high pressure water jet cutting withthe high frequency rock fragmentation, and by means of the sheet-likedesign of the drill head 2 and the corresponding positioning of thewater outlet nozzles 8 and sonotrodes 9, in the illustrated exemplaryembodiment it is possible to carry out the drilling operationcontinuously, that is to say without interruptions for refurbishing adrill bit or for removing a cut-free drill core, as is required in thedeep drilling methods known from the prior art.

In order to be able to use a continuously operating drilling method asefficiently as possible, it is advantageous if the borehole 5 can alsobe secured and lined substantially continuously.

In order to secure the borehole 5 and also in order to shield theborehole from groundwater-conducting layers, the borehole 5 is lineddirectly after drilling. For this purpose, the borehole lining module 4according to the invention has spray nozzles 11 for applying a curingmedium, such as, for example, concrete, and a reinforcing fabric layingapparatus 12.

Use is preferably made of carbon fibers and concrete in order to producethe hybrid material serving for lining the borehole wall, but otherfiber materials and other curing media, such as, for example, plastics,are also usable for producing the hybrid material.

The reinforcing fabric laying apparatus 12 for discharging the fiberstructure can take place, for example, via a cone, via which thereinforcing fiber can be applied directly onto the borehole wall inorder subsequently to be able to be wetted with curing medium. Dependingon the depth and geological conditions, the borehole 5 can be lined withone layer or with multiple layers. The curing time of the concrete canbe accelerated by the addition of special additives. In deeper regionswith a higher earth temperature, the curing time is reduced simply bythe rise in temperature. The concrete supplied via the pipe and/or hoselines is mixed with the additives, which are likewise supplied via thepipe and/or hose lines 6, only at the borehole lining module 4, in orderto avoid curing in the supply lines.

A finished borehole lining 18 is illustrated schematically in FIG. 3.

The safety module 3 serves, in the event of a sudden rise in pressure inthe borehole 5, for example by drilling into a gas bubble, firstly toprevent uncontrolled escape of the gas from the borehole 5 and secondlyto prevent the entire drilling system 1 from being able to be pushedupward out of the borehole 5 by the rise in pressure. For this purpose,the safety module 3 has at least one locking element 13 for theform-fitting closing of the inside diameter of the borehole and clampingelements 14 for the force-fitting securing of the drilling system 1 inthe borehole 2.

The diameter of the borehole is closed in a form-fitting manner via thelocking element 13, for example with an expander ring which closes theborehole 5, in order then to be able to dissipate the positive pressurein a controlled manner via suitable pressure control valves. Theclamping elements 14 with which the entire drilling system 1 caninterlock in a force-fitting manner in the borehole 5 are designed, forexample, as barbs which face radially upward and outward and fix thedrilling system 1 in the respective position in the borehole 5 as theneed arises.

The drive and also the steering and control apparatus for the drill head2 are arranged on the drill head 2. In the embodiment illustrated, thedrive for the drill head 2 is designed as a crawler drive 15 arranged onthe outer side of the drill head 2.

In addition to the electric supply lines, the flexible pipe and/or hoselines 6, via which the drilling system 1 is connected to supply devices7 outside the borehole 5, also contains data lines, for example a bussystem, via which the drill head 2 and/or the safety module 3 and/or theborehole lining module 4 are connected to a workplace 16 outside theborehole 5.

Via said data lines, in addition to the system parameters, such as, forexample, feed speed and pumping pressure, all of the ambient parametersin the borehole 5, such as, for example, temperature, pressure, rockdensity and the like, can be determined via sensors coupled to the datalines and can be transmitted to the workplace 16 in order to control thedrilling system 1.

Since, in the illustrated drilling system 1, in particular, the drillhead 2 has a larger outside diameter than the fully lined borehole 5,after the end of the drilling operation the entire drilling system 1remains in the borehole 5 and, after the capping of the supply lines,can be used via the data lines which continue to exist, in order toexchange data with the workplace 16.

Should it be necessary in an alternative drilling method or when analternative drill head is used for said drill head to be removed fromthe borehole 5 in the meantime or at the end of the drilling operation,said alternative drill head has to be configured, for example, in afoldable manner, such that the outside diameter thereof can be reducedsuch that said drill head is moveable through the finished boreholelining 18.

The control of the drilling system 1 can be arranged on only one of thecomponents of drill head 2, safety module 3 or borehole lining module 4,or else can be arranged distributed between a plurality of thecomponents 2, 3 and 4.

The borehole lining method which is described above and is usable forgeothermal bores and for opening up natural gas or oil deposits isdistinguished in that a virtually continuous lining of the boreholedirectly after drilling is made possible. Furthermore, the boreholelining 18 has a substantially constant cross-section over the entirelength of the borehole.

1. A method for lining boreholes for deep bores, characterized in thatthe borehole is lined directly after drilling with a hybrid materialconsisting of a fiber material and a curable medium.
 2. The method asclaimed in claim 1, characterized in that the wall of the borehole iscontinuously lined.
 3. The method as claimed in claim 1, characterizedin that the curable medium is sprayed onto the fiber material.
 4. Themethod as claimed in claim 1, characterized in that the hybrid materialcan be applied onto the borehole wall in one layer or in multiplelayers.
 5. An apparatus for carrying out the method as claimed in claim1, characterized by a borehole lining module which has spray nozzles forapplying a curing medium, and a reinforcing fabric laying apparatus. 6.The apparatus as claimed in claim 5, characterized in that the boreholelining module is connected to supply devices outside the borehole viaflexible pipe and/or hose lines, wherein the pipe and/or hose linesserve for the supply and removal of the materials relating at least tothe borehole lining module and for the feeding in of the electric supplylines.
 7. The apparatus as claimed in claim 5, characterized in that atleast the borehole lining module is connected to a workplace outside theborehole via data lines, for example a bus system.
 8. The apparatus asclaimed in claim 7, characterized in that, via the data lines, inaddition to the system parameters, such as, for example, feed speed, allof the ambient parameters in the borehole, such as, for example,temperature, pressure, rock density and the like, can be determined viasensors coupled to the data lines and can be transmitted to theworkplace in order to control the borehole lining module.